1. Field of the Invention
The present invention relates to a pointing device which can be suitably provided in a data processor such as a personal computer.
2. Description of the Related Art
In a digital data processor, such as a personal computer, provided with a display and a keyboard incorporated therein, a pointing device is conventionally used as an auxiliary input device for indicating coordinate data on the display by entering analog information through a manual operation by an operator. Particularly, a typical small-sized portable data processor is provided with a built-in type pointing device integrally incorporated in a housing body of the data processor, or otherwise a separate pointing device, such as a mouse, is detachably connected with the processor housing body through a cable and a connector when it is used.
The conventional pointing device, described, e.g., in Japanese Unexamined Patent Publication (Kokai) No. 10-49292 (JP-A-10-49292), includes a base part, an operating part supported on the base part and rockable about a fulcrum provided on the base part, a magnet carried on one of the base part and the operating part, a magneto-electro transducer (generally, a Hall element) carried on the other of the base part and the operating part opposite to the magnet, and an elastic member for pushing or biasing the operating part toward an initial balanced position on the base part. In this pointing device, an operator manually operates the operating part to rock it on the base part against the biasing force of the elastic member, and changes the positional relationship between the magnet and the magneto-electro transducer to vary the output voltage of the magneto-electro transducer, whereby it is possible to enter analog information corresponding to the rocking direction and rocking angle of the operating part.
In the case where the above pointing device having the magneto-electro transducer is integrally incorporated in the housing body of the small-sized data processor, the pointing device is mounted with the operating part thereof being exposed on the upper side portion of the housing body adjacent to the keyboard of the data processor. In this arrangement, the height of the operating part projecting from the upper side of the housing body is reduced as much as possible, in order to ensure the portability of the data processor. Particularly, when it is required to facilitate the reduction of thickness of the data processor, the pointing device is also required in itself to be reduced in the height thereof, i.e., a distance between the bottom surface of the base part and the top surface of the operating part should be decreased as much as possible.
Incidentally, the built-in type pointing device as described above essentially imposes an input operation within a limited area on a operator, and besides, there is a possibility of further deteriorating the operational properties when the height reduction is facilitated. Therefore, in the case where the operator regards the good operational properties of the pointing device as important when using the data processor with a reduced thickness, a detachable type pointing device, in which the dimensions are not related to the dimensions of the data processor, is used. In particular, when the data processor is used in a portable way, it is difficult to ensure a space for operating a mouse having a normal structure, in which an operative ball is partially exposed on the back side of the mouse. Consequently, it has been proposed that a pointing device having a structure similar to that of the conventional built-in type pointing device is used while being detachably attached to the housing body of the data processor (see, e.g., Japanese Unexamined Patent Publication (Kokai) No. 6-139013 (JP-A-6-139013)).
When it is required to reduce the height of the conventional pointing device having the magneto-electro transducer, it is also required to decrease the dimension of the components of the pointing device in a vertical direction, corresponding to height in the assembled state thereof. However, if the dimension in a vertical direction of the elastic member, generally formed by a rubber or a coil spring for biasing the operating part toward the initial position, is excessively reduced, it is possible that a spring force generated when the elastic member is elastically deformed becomes insufficient, which may result in a difficulty in the proper and stable operation of the operating part. Also, if the dimension in a vertical direction of the respective components is decreased, problems may arise wherein the distance between the magnet and the outer surface of the operating part exposed on the upper side of the housing body of the data processor is inevitably reduced, and thereby facilitating magnetic leakage through the operating part to the exterior thereof.
On the other hand, the conventional detachable pointing device, described, e.g., in JP-A-6-139013, includes a housing accommodating both an operating part and a detecting section for detecting the movement of the operating part. When the detachable pointing device is used, a cable extending from the housing is connected through a connector to the data processor, and the housing is mounted at a desired position on the housing body of the data processor. In this arrangement, it is generally troublesome to electrically connect and mechanically attach the pointing device with the data processor, and the cable extending around the data processor from the pointing device mounted thereon may deteriorate the portability and operational environmental condition of the data processor.